The present invention relates to a cylinder apparatus for use in a suspension system of an automobile, for example.
Examples of cylinder apparatus include a tube-type hydraulic shock absorber attached to a suspension system of an automobile. In such a cylinder apparatus, the open end of a cylinder may be closed by using a closing structure as disclosed in Japanese Patent Application Publication No. 2004-251413. With this closing structure, after a seal case and an oil seal have been inserted into the cylinder, the open end of the cylinder is staked or caulked to prevent the extraction of the seal case and the oil seal from the cylinder. In a high-pressure cylinder apparatus as disclosed in Japanese Patent Application Publication No. 2005-133902, a cap is threaded onto the open end of the cylinder.
The closing structure in which a cap is threaded onto the open end of the cylinder is inferior in productivity. It is therefore desirable to use staking or caulking to close the open end of the cylinder. In cylinder apparatuses in which a high hydraulic pressure acts in a gas chamber, however, the staked or caulked portion is subjected to a great force. Therefore, it is desired that these cylinder apparatuses have further increased pressure resistance.